Did some fab work on my friends dart sport stocker last spring in prep for the race season(new drive shaft loop). we disconected all the electronics , ply back tach msd box ground to battery did not disconect the ground from the engine to the firewall.Welded up the mounts for the loop to the subframe connectors.the car was 2 tenths slower than the first race last year and was very hard to push . we could not figure it out , but talked to another friend , said he welded on his car and the ground some how back fed through the trans and burned from a bearing surface to the rear out put shaft.We were skeptical but pulled the trans and sent it to our trans guy ,bingo. I would try everything else first, very unusual but it happened naturaly i got the blame because i was the welder